This invention, which resulted from a contract with the U.S. Department of Energy, relates to a calibration means. More particularly, the invention relates to a standard having a perimeter with a precise out-of-round configuration that can be used to more accurately calibrate roundness testing machines than has been possible with conventional calibration standards.
For several decades laboratories throughout the world have set the readout of roundness testing machines by use of precisely machined cylindrical standards each having a narrow flat surface extending lengthwise thereof. As will be shown in further detail hereinafter, it has been determined that this type of roundness standard is not suitable for calibrating test machines that measure deviations from roundness in microinches.